4. Discussion
We believe that the selection of L. monocytogenes and L. innocua strains derived from
different profiles allowed us eliminate bias as a factor in our results. Three pairs of serovar 4b
strains used in the study were isolated at different times from clearly unrelated samples and
all had similar RAPD profiles. Therefore, they were not a group of genetically related
strains. Other L. monocytogenes, and all of the L. innocua, strains showed different RAPD
profiles, even if they belonged to the same serovar.
The inhibition of L. monocytogenes by some strains of L. innocua during enrichment
culture was not due to the difference of generation times between the Listeria species.